Even minute quantities of dioxin in a pregnant woman may cause shrinkage of her son's prostate gland and weaken his immune system, according to the results of recent experiments on rats conducted by a Japanese scientist.
Junzo Yonemoto of the National Institute for Environmental Studies said that after administering a pregnant rat with 800 nanograms of dioxin per kilogram of body weight, the male offspring's prostate gland weighed 60 percent of that born to another female not given the dioxin. One nanogram is one-billionth of a gram.
The experiment involved giving four groups of pregnant rats 12.5, 50, 200 and 800 nanograms of dioxin per 1 kg of body weight, respectively.
The results also showed that the prostate glands of male rats whose mothers were given 200 nanograms of dioxin shrunk in weight by 20 percent.
"The concentration of dioxin in the affected rats' blood is only 10 times that in human beings. We must investigate more carefully the effects of dioxin on a mother's constitution and her children," said Yonemoto.
The institute, in Tsukuba, Ibaraki Prefecture, is an affiliate of the Environment Agency.
Moreover, the length between the male's genital organ and anus, which represents the degree of maleness, was found to be shortened by 13 percent on rats in the 50-nanogram group, he said.
The shorter the length, the stronger the feminization of the male.
The dioxin levels in the pregnant rats' bodies also reduced the number of cells in the thymus and spleen, which control the immunity system, the study said.